Two-Phase CFD and PIV EFD for Plunging Breaking Waves, Including Alternative CFD Approaches and Extensions for Air/Water Ship Flow

This paper represents a first step towards the development of two-phase CFD methods for small and large scale ship hydrodynamic applications. Two-phase level set approaches are being implemented in CFDShip-Iowa to extend the modeling capabilities of the current version 4 along with complementary experiments for validation. The experiments are conducted in an open channel flume using bottom mounted bumps to generate plunging breaking waves. Experimental work includes determining the optimum flow conditions for generating periodic and impulsive plunging breaking waves, theoretical analysis for free surface instabilities that are observed at low speeds prior to the breaking process, and experimental measurements for validation of the theory. Two twophase level set methods, the Heaviside function method (HFM) and the ghost fluid method (GFM) are extended to curvilinear body-fitted grids to simulate air/water free surface turbulent flows and the methods are applied to plunging wave breaking, sub-critical free surface flows generated by a submerged bump, and free surface turbulent flow both in air and water around a ship model DTMB 5512. The results show good agreement with experimental data. Another method using two-phase level set embedded boundary Cartesian grid, has also been implemented and results are presented for some preliminary computations. The simulation of impulsive plunging breaking waves is in very good qualitative agreement with the experimental data. A computation of non-breaking waves generated by a submerged hydrofoil has also been carried out and the results compared very well with the experimental data.